In China, running has witnessed rapid growth as a popular endurance sport, driven by the continued implementation of the National Fitness Strategy and the booming development of road running events. According to data released by the Chinese Athletics Association, over 700 road races were held across the country in 2024, attracting more than 7 million participants (1).

Rehydration is critical to human health and athletic performance (2), especially for marathon athletes. As a typical long-distance endurance sport, marathons often expose athletes to extreme climatic conditions, such as high temperatures and humidity, for extended periods during training and competition. These conditions substantially increase sweat loss, leading to considerable water and electrolyte depletion (3). Inadequate or untimely rehydration may predispose athletes to hydration-related illnesses (4, 5). Therefore, maintaining stable hydration during marathons is not only key to sustaining athletic performance but also an essential safeguard against health risks.

However, for marathon runners, maintaining dynamic hydration balance—the ongoing regulation and fluctuation between fluid intake and sweat loss (6)—during daily training and competition presents multiple physiological challenges, primarily due to the effects of persistent sweat loss and electrolyte depletion on plasma volume stability and intracellular fluid balance (7). This process is highly susceptible to dysregulation due to individual differences in athletes’ responses to environmental temperature, humidity, and exercise intensity (8), which can affect their health and performance. Existing studies indicate that the oxygen uptake of runners of varying levels during marathon exercise ranges from 60 to 86% of VO₂ max (9), and the hourly sweating rate of adult participants can reach 1.2 to 2.5 L/h. This is accompanied by significant electrolyte loss, with sodium ion (Na+) loss reaching up to 20–80 mmol/L (10). Water and Na + deficiency are considered risk factors for exercise heat stroke (11, 12), exertional heat exhaustion, and exertional heat cramps (13). Dehydration impairs physiological functions, leading to decreased athletic performance (14–16), excessive consumption of plain water without electrolyte supplementation may dilute blood sodium concentration and induce symptoms of hyponatremia (17).

Currently, the number of marathons organized and the number of participants in health promotion-oriented marathons in China are increasing (18). However, systematic studies on the attitudes, knowledge, and behaviors regarding rehydration among Chinese recreational marathon runners remain relatively scarce. Although some research on sports rehydration has been conducted, most studies focus on professional athletes and college students, with fewer addressing Chinese recreational marathon runners (19–23). Compared to professional athletes, recreational marathon runners differ significantly in exercise level, training mode, and physical condition (24); their rehydration needs and behavioral characteristics also vary. Existing studies suggest that the post-race fluid loss of recreational marathon runners who finish at a low intensity is generally below the physiological critical threshold of 2% of body weight (25). However, under conditions of high temperature (above 30°C), high humidity (relative humidity above 70%), or complex terrain, their sweat loss rate may increase non-linearly (7), potentially exceeding the 2% body weight threshold affecting exercise performance. This can result in an increased cardiovascular load and compensatory dysregulation of thermoregulatory functions, presenting potential risks (26).

Therefore, the aim of this study is to investigate the daily hydration behavior of recreational marathon runners in China, to understand their hydration practices and strategies during running, and to analyze the influence of factors such as gender, age, and performance level on their hydration behavior, knowledge, and attitudes. The findings aim to provide a theoretical basis for developing evidence-based hydration guidelines, optimizing health risk management, and enhancing athletic performance.

Optimal hydration is critical for maintaining homeostatic regulation of organ systems and biochemical equilibrium (31). However, this study found that Chinese recreational marathon runners were generally under-hydrated. Based on the standard of 1,500 mL to 1700 mL of water per day for normal adults, as recommended in the Dietary Guidelines for Chinese Residents (2022) (30), only 27.5% of participants were able to meet this minimum threshold. This rate is notably lower than the 67.6% reported by Zuo et al. (32) for cities such as Beijing, Shanghai, Guangzhou, and Chengdu, or the 60% reported by Malisova and Athanasatou et al. (33) in European countries, and by Shaheen et al. (34), who noted that the water intake of populations in the Middle East met the recommended standard. However, it is similar to the attainment rates reported by Martinez et al. (35) for Mexico (10–25%) and Brazil (21%). The achievement of the daily water intake standard varied across studies, potentially due to differences in external factors (e.g., geographic characteristics, climatic conditions), sociocultural context (e.g., dietary habits, ethnic lifestyles), and study design characteristics (e.g., sample size, age group stratification). Particularly concerning is the observation that 22.3% of participants had a daily water intake of less than 800 mL. Given the impact of exercise and heat stress on body water homeostasis, and referencing foreign studies indicating higher water intake among individuals with elevated exercise levels (36–38), it is hypothesized that Chinese recreational marathon participants may experience chronic mild dehydration for extended periods or may even be dehydrated before training. This variability underscores the need for education among Chinese recreational marathon runners regarding rehydration to enhance their understanding and help mitigate health risks. Furthermore, this study revealed that the proportion of insufficient water intake was significantly higher among” Not Certified” runners compared to “Public Elite” runners. This discrepancy may reflect differences in daily training mileage or hydration awareness among performance levels. Collectively, the results suggest that while hydration knowledge and practices may improve with athletic performance level, overall water intake among Chinese recreational marathon runners remains inadequate.

An accurate assessment of an individual’s hydration status is a fundamental component of a scientific rehydration strategy. The presence of dehydration can typically be identified through thirst signals and urine color, with the latter serving as a simple yet effective indicator of daily hydration status (39). However, the present study revealed that 54.9% of participants relied on thirst as their primary indicator of hydration status, and 46.9% were unaware of the urine color that corresponds to adequate hydration. Notably, a higher proportion of participants under the age of 34 reported using thirst signals as their primary cue for hydration. The physiological phenomenon of lagged thirst may contribute to a detrimental cycle in which individuals experience dehydration, fail to adequately rehydrate, and subsequently exacerbate their dehydration, particularly during physical exertion (40, 41). This cycle increases the risk of fluid and electrolyte imbalance, especially among those who train frequently. These findings suggest that Chinese recreational marathon runners generally lack scientific understanding of fluid replacement and hold misconceptions regarding accurate self-assessment of hydration status, which may contribute to their insufficient daily fluid intake. Despite some degree of awareness, only 27.5% of participants met the recommended daily water intake, reflecting a disconnect between perceived hydration awareness and actual fluid consumption. This further amplifies the risk of chronic, subclinical dehydration. The general neglect of dehydration risks, limited self-regulated fluid intake, and poor monitoring of hydration biomarkers, particularly urine color, which can be easily observed visually, highlight the urgent need to integrate biomarker-based education into public hydration strategies. Therefore, future efforts should prioritize the widespread dissemination of fluid replacement knowledge among Chinese recreational marathon runners, with a focus on improving daily hydration practices and fostering greater awareness of the critical link between proper hydration, athletic performance, and long-term physical health.

Scientific hydration strategies are essential for maintaining physiological function during marathon exercise. Prolonged high-intensity running relies heavily on evaporative heat loss to maintain core temperature homeostasis (17, 42), during which substantial water and electrolyte losses are inevitable. Numerous international studies have demonstrated that inappropriate rehydration behavior can compromise both health and athletic performance. On the one hand, excessive intake of pure water dilutes body water, accompanied by sweat sodium loss, which can lead to a dilutional decrease. risk of exercise-associated hyponatremia (43); on the other hand, inadequate fluid intake may impair thermoregulation and cardiovascular function, heightening the risk of heat stroke, exertional rhabdomyolysis, and a marked reduction in aerobic capacity (44), especially in endurance athletes.

In this study, we examined the rehydration behaviors of Chinese recreational marathon runners across three critical stages—before, during, and after competition—and identified widespread misconceptions regarding appropriate hydration practices. The core issues centered on the persistent risk of inadequate fluid intake and the general lack of scientific rehydration strategies. According to recommendations by the American College of Sports Medicine (ACSM), sodium-containing fluids should be consumed at a volume of 5–10 mL/kg approximately 2 h prior to competition to optimize hydration status (45, 46). However, 57.7% of the participants in our study reported consuming only 150 mL of fluids prior to the race, and the majority selected plain water as their primary source of hydration. This combination of insufficient volume and electrolyte deficiency was not confined to any particular subgroup, suggesting that a large proportion of recreational runners may begin competition in a state of pre-existing dehydration. These findings are consistent with previous reports by Maughan and McCrink et al. (47, 48), who observed that many athletes were already dehydrated prior to exercise. Collectively, the results reinforce our hypothesis that Chinese recreational marathon runners may experience chronic mild dehydration, and in some cases, may remain persistently dehydrated throughout the duration of the race.

Fluid replacement during exercise is calculated based on exercise intensity and sweat rate (49). Noakes and Martin et al. (50) recommend that athletes aim to consume 400–800 mL of fluid per hour during endurance activities. However, the present study found that many Chinese recreational marathon runners consumed only 150 mL of fluid during the race. This suggests that nearly half of these runners may experience dehydration during competition. This phenomenon may be attributed to concerns over gastrointestinal discomfort caused by fluid intake during exercise (51). Therefore, it is recommended that runners develop individualized hydration strategies aligned with their physiological status, training level, environmental conditions, and event-specific demands. To improve gastrointestinal tolerance to fluid intake, athletes should also engage in periodic gut training during exercise. Additionally, fluid consumption should be adjusted according to race duration and environmental heat stress. Notably, the current findings diverge from previous studies reporting higher fluid intake among runners with less marathon experience, slower training paces, or longer race durations (52–54). In contrast, our study observed lower in-race fluid intake among Chinese recreational marathon runners, with no significant variation across performance levels. This indicates a general lack of awareness regarding hydration practices and a greater susceptibility to exercise-induced dehydration in this population. Interestingly, female runners were more likely to select fluid volumes of 750 mL or more during the race, a finding consistent with international studies (43, 52). This may reflect both greater hydration awareness and physiological differences (e.g., smaller body mass and greater concern over fluid loss), but it may also increase the risk of exercise-associated hyponatremia if sodium is not adequately replenished.

Post-exercise fluid replacement is essential for supporting physiological recovery and restoring homeostasis. It is generally recommended that fluids lost during exercise be replenished at a rate of approximately 125–150% of the fluid deficit—typically, 1.25 to 1.5 liters of fluid per 1 kg of body weight lost—alongside appropriate sodium supplementation to restore water-electrolyte balance and maintain systemic fluid homeostasis (55, 56). The present study also found similar behavior to Judge et al. (22), who observed a lack of voluntary hydration among participants following exercise; Nearly half of Chinese recreational marathon runners chose to replenish only 150 mL of fluid after the race. This may be related to factors such as professional rehydration knowledge, biased understanding of scientific advice, and inadequate design of rehydration stations and environments. In addition, there was significant variability in insufficient hydration by performance levels, with runners with high levels of athleticism being able to recognize the role of post-exercise hydration in promoting physiological recovery and being more likely to adopt positive hydration behaviors. These findings are consistent with previous research emphasizing the importance of hydration attitudes in influencing rehydration intake behavior (57).

In this study, we found that a higher proportion of Chinese recreational marathon runners consumed sports drinks during the race (56.6%) compared with the 50% reported by Felder et al. (58). To prevent dehydration and delay the onset of exercise fatigue and “hitting the wall” (59), it is necessary to consume a certain proportion of carbohydrates and electrolytes during marathon races to promote enhanced fluid absorption and supports sustained exercise performance (46). The nutritional value of plain water alone generally lacks the nutritional components necessary, while the additional sports drink intake can fulfill these needs (60) and provide a convenient option for runners who may not have prepared specialized rehydration fluids in advance. Notably, significant gender differences were observed in post-race consumption of carbonated beverages. Female runners were more likely to consume such drinks, which may reflect a greater preference for sweetness or a form of emotional compensation following strenuous exercise. Women tend to have higher body fat and lower fat-free mass, with elevated leptin levels and a more sensitive ghrelin response. This makes them more likely to consume sweet foods after exercise as a rapid means of restoring energy and achieving psychological comfort (61). Additionally, women’s eating behaviors are more strongly influenced by emotions, and the psychological association between sweet foods and emotional consolation may further reinforce their preference for high-sugar foods. However, the high-sugar, low-sodium nature of carbonated beverages may interfere with water absorption and exacerbate electrolyte loss and the CO₂ gas released there may also exert greater stress on the gastrointestinal lining (62), causing greater renal oxidative stress and mild renal injury, especially after ingestion of fructose-rich beverages in a dehydrated state (63). Despite these potential risks, 15.6% of participants still chose carbonated beverages post-race, likely due to the psychological satisfaction derived from their distinctive flavor and sensory stimulation.

Data on sources and strategies of rehydration during the race reflect the diversity and variability in rehydration behaviors among recreational marathon runners in China. The survey revealed that some participants did not follow a structured rehydration plan and instead relied on thirst cues during the race. Similar patterns have been reported in previous studies (19, 22, 64, 65), especially among females and the “Not Certified” participants. A key contributing factor to this phenomenon is insufficient knowledge regarding hydration. The present study confirmed that runners with higher performance levels were significantly more likely to formulate a pre-race hydration plan (66). In addition, health-related concerns were identified as major motivational drivers for behavioral change. A substantial majority of participants (95.2%) acknowledged the importance of hydration for maintaining health, and 93.3% expressed a willingness to modify their hydration practices to enhance performance. These findings are consistent with prior research indicating that health awareness and performance goals jointly motivate positive behavioral adaptations (20, 23). Collectively, these results underscore the presence of outcome-oriented behavioral change tendencies among Chinese recreational marathon runners and highlight the urgent need for targeted educational interventions aimed at promoting scientifically informed hydration practices.

Based on the correct responses to the participants’ knowledge of rehydration, it was found that their understanding of the field of scientific rehydration was low. The results of this study were similar to those of Chi et al. (67). Only 21.5% of the respondents were aware of the recommended daily water intake. Assessing an individual’s hydration status is also a key element of a scientific rehydration strategy. Urine color is a simple and effective indicator for evaluating daily hydration status (39). The survey showed that only 53.1% of Chinese recreational marathon runners could correctly identify a healthy urine color. The findings of the present study confirm those reported by Rosenbloom et al. (68) and Spokely et al. (69), indicating a widespread knowledge gap in hydration across the general population, making it difficult for individuals to maintain adequate hydration. Overall, the low level of hydration knowledge among Chinese recreational marathon runners highlights the urgency of enhancing health education and incorporating biomarker monitoring into hydration education.

The present investigation found that family and friends (54.9%), social media (45.6%), and books and magazines (40.8%) were the main sources of knowledge about rehydration for runners, but the quality of information from these sources varied, which may lead to runners obtaining incomplete or incorrect health knowledge. In contrast to Nieper’s (70) study, in which 75.0% of athletes had access to a sports dietitian, only a minority of participants in this study had access to a sports dietitian (16.3%) or a coach (28.6%). This highlights the underrepresentation of professionals in mass fitness; one contributing factor may be the free and unsystematic nature of the participants’ training routines. On the other hand, the services of sports dietitians and professional coaches may be constrained by factors such as geographical limitations and cost, making it difficult for some runners to obtain professional guidance. Therefore, it is recommended to strengthen the knowledge, attitudes, and education related to scientific fluid replenishment among Chinese recreational marathon runners, to help this population recognize the close relationship between hydration, athletic performance, and physical health, ultimately aiming to promote physical well-being and enhance athletic capacity.

Although this study systematically evaluated the hydration knowledge, attitudes, and behaviors of Chinese recreational marathon runners, certain limitations remain. First, as a cross-sectional design was employed, causal relationships between hydration behaviors and health outcomes cannot be established. Second, the data were primarily based on self-reported information, which may be subject to recall bias or social desirability bias—particularly in measures such as daily fluid intake and hydration practices—potentially resulting in discrepancies from actual behavior. Third, although the sample included participants from various regions and events, there was some imbalance in geographic and age distribution, which may limit the generalizability of the findings.

Nevertheless, this study represents the first nationwide systematic investigation of hydration practices among recreational marathon runners in China. It identified widespread issues such as insufficient daily fluid intake, inadequate hydration during race periods, and limited knowledge levels. These findings provide empirical evidence for the development of targeted health education strategies aimed at improving hydration behaviors within this population.

Future research should explore the unique characteristics of the Chinese population in terms of body composition, physiological parameters, and lifestyle, in order to develop hydration strategies and intake guidelines that are better tailored to the specific needs of East Asian populations. Specifically, future studies should focus on key parameters such as fluid type, hydration volume, and electrolyte concentration to construct individualized hydration plans that are both targeted and scientifically sound, meeting the physiological demands of different populations under varying environmental conditions and exercise intensities. In addition, further research may be needed to specifically examine the relationship between athletic performance level and fluid intake. Meanwhile, emphasis should be placed on building self-monitoring capabilities for hydration status, shifting runners from passive to active hydration management. It is recommended to integrate modern wearable devices and digital health tools to develop self-assessment scales or intelligent systems based on indicators such as urine color, body weight change, and sweating rate, thereby enabling runners to dynamically evaluate their hydration status and receive behavioral feedback to improve the proactivity, scientific rigor, and timeliness of their hydration practices.

In summary, the results of this research study suggest that daily underhydration is very common among Chinese recreational marathon runners (72.5%), and that underhydration behaviors during races are even more pronounced and not restricted to a specific subgroup. A lack of knowledge about hydration is the main reason for this phenomenon. These findings highlight the need to educate this population with scientific knowledge on proper hydration.

Meanwhile, the findings of this study also provide empirical evidence to inform both race organizers and individual athletes in developing targeted intervention strategies. It is recommended that recreational marathon runners enhance their awareness and behavioral capacity regarding scientific hydration management. Particularly during routine training, greater emphasis should be placed on the dynamic assessment of individual hydration status. For example, simple indicators such as urine color and body weight changes can be used to identify potential dehydration risks in a timely manner, thereby gradually fostering proactive and evidence-based hydration habits.

In races of varying distances, the density and placement of hydration stations, the types of beverages provided, and the delivery methods should all be scientifically tailored according to real-time meteorological conditions on race day—such as temperature, and humidity—as well as racecourse characteristics, including elevation profile, shading, and terrain complexity, in order to optimize fluid replacement efficiency.